It is known to carry out the activation of lignite coke in a rotary tube after the addition of 25% aqueous potassium carbonate (compare Chem. Techn. Volume 34 (1982), pages 290-300).
From Ullmann's Enzyklopadie der technischen Chemie, 4th edition, volume 14, pages 623, 625, and 626 there is known the gas activation of lignite coke with addition of solid potassium carbonate or potassium carbonate dissolved in water before the activation.
The known processes have the disadvantages that there cannot be obtained an especially finely pored activated carbon.
In the known processes the lignite coke is suspended in the aqueous catalyst solution before the true activation. Through this there is absorbed by the lignite coke a non-controllable amount of catalyst, depending on the quality of the lignite. The impregnated brown lignite coke of this type is filtered off in the known process, dried, and subjected to the actual activation.
Because the absorption on the catalyst cannot be controlled exactly, it is not possible to reproducibly produce a predetermined activated carbon quality.
Futhermore activated carbon produced according to the known process has the disadvantage that it is not particularly successful in the removal of chlorohydrocarbons in the preparation of drinking water from ground water or in the preparation of sewage.